Passive dosing dispenser exhibiting improved resistance to clogging

ABSTRACT

A passive dosing dispenser for issuing, for example, a predetermined volume of a liquid toilet tank additive solution into a toilet tank as the water is draining therefrom while the toilet is flushing. A preferred dispenser comprises an internal reservoir having a product chamber for containing a quantity of a solid type product which can be dissolved in water to form a toilet tank additive product solution and a liquid solution reservoir for containing a quantity of said solution in fluid communication with said product chamber, and inlet/discharge conduit having its lowermost end in fluid communication with said liquid solution reservoir and its uppermost end in fluid communication with a syphon tube, and air trap disposed adjacent said inlet/discharge conduit for isolating said liquid product solution from the toilet tank water in said syphon tube during quiescent periods, and an air vent in fluid communication with said liquid solution reservoir and said product chamber. To accommodate solid type products which have a tendency to form a gel while dissolving, novel clog prevention, i.e., anti-clogging means are provided within the dispenser to limit the amount of non-gelled solid product exposed to liquid and to maximize the area of contact between the liquid contained within the dispenser and the gelled product. The novel anti-clogging means helps ensure that dispensing of a predetermined quantity of the liquid solution will occur with each flush cycle of the toilet.

TECHNICAL FIELD

The present invention pertains, in general, to providing a dosing typedispenser for such products as liquefied toilet tank additives: forinstance, disinfectants, aerosolization retardants, and the like. Morespecifically, the present invention provides an entirely passive (nomoving parts) dispenser in which a solid type product will gradually bedissolved to form a solution, and from which dispenser such solutionwill be incrementally issued: a predetermined quantity or dose-volume ofsolution being issued each time the water in the toilet tank recedesfrom around the dispenser. In particular, dispenser embodiments of thepresent invention permit effective dispensing of liquid solutions formedfrom solid type products which have a tendency to form hydrated gelswhile undergoing dissolution. Dispenser embodiments of the presentinvention also provide means for make-up water to enter the dispenser,and air-lock isolation of the solid product, the incompletely dissolvedgel and the liquid product solution within the dispenser from thesurrounding toilet tank water during quiescent periods. Plural productdispenser embodiments are also provided which can, because each segmentprovides isolation from the toilet tank water during quiescent periods,co-dispense solutions of two or more products which should not be mixedbefore their intended use.

BACKGROUND ART

Passive dosing dispensers of various geometries are disclosed in priorart patents. For instance, U.S. Pat. No. 650,161 which issued to J.Williams et al. on May 22, 1900 and U.S. Pat. No. 1,175,032 which issuedto E. R. Williams on Mar. 14, 1916 disclose passive dispensers which arealternately flooded and then syphoned to a predetermined level. Also,U.S. Pat. No. 3,772,715 which issued to L. V. Nigro on Nov. 20, 1973,and U.S. Pat. No. 3,781,926 which issued to J. Levey on Jan. 1, 1974,and U.S. Pat. No. 3,943,582 which issued to J. Daeninckx et al. on Mar.16, 1976 disclose passive dispensers which are alternately flooded andthen gravitationally drained. Moreover, U.S. Pat. No. 3,407,412 whichissued to C. T. Spear on Oct. 29, 1968, and U.S. Pat. No. 3,444,566which issued to C. T. Spear on May 20, 1969 disclose dispensers which,although they have no moving parts, must be connected to a pressurizedwater supply such as the trap refill tube in a toilet tank and in whichthe direction of flow alternates in labyrinth passages.

Passive dosing dispensers of the type disclosed in the commonly assignedpatent application of Robert S. Dirksing entitled PASSIVE DOSINGDISPENSER EMPLOYING TRAPPED AIR BUBBLE TO PROVIDE AIR-LOCK, Ser. No.002,524, filed Jan. 11, 1979, which is hereby incorporated herein byreference, have solved many of the problems associated with theaforementioned prior art dispensers, most particularly the problem ofproviding solid product and liquid product solution isolation fromsurrounding toilet tank water during quiescent periods. Dispenserembodiments of the type generally disclosed in FIGS. 1 and 15-18 of theaforesaid patent application of Robert S. Dirksing have been foundparticularly suitable for dispensing liquid solutions formed from solidproducts containing a surfactant. However, when the solid productexhibits a substantial tendency to form a hydrated gel while undergoingdissolution, even dispensers of the type disclosed in FIGS. 1 and 15-18of the aforementioned patent application of Robert S. Dirksing mayfunction with less than complete reliability due to the presence ofexcessive quantities of the incompletely dissolved gel within thedispenser.

DISCLOSURE OF INVENTION

In accordance with one aspect of the invention, a dispenser is providedwhich comprises an internal reservoir having a product chamber forcontaining a quantity of a solid product in fluid communication with aliquid solution reservoir for containing a quantity of liquid productsolution, and means for causing a predetermined quantity or dose-volumeof said liquid solution to be conducted from said liquid solutionreservoir and issue from the dispenser in response to the level of abody of liquid in which said dispenser is immersed being lowered from afirst elevation to a second elevation. Such a dispenser can comprise aninternal reservoir having a product chamber and a liquid solutionreservoir in fluid communication therewith, a syphon tube extendingdownwardly from said liquid solution reservoir and having an open lowerend, an inlet/discharge conduit having an air trap disposed adjacentthereto, said conduit having its lowermost end in fluid communicationwith said liquid solution reservoir and its uppermost end in fluidcommunication with the uppermost end of said syphon tube, and an airvent in fluid communication with said liquid solution reservoir andproduct chamber.

The air trap disposed adjacent the inlet/discharge conduit acts toretain an air bubble when water enters the liquid product solutionreservoir via the syphon tube and inlet/discharge conduit as the waterin the toilet tank returns to the FULL level. As long as water isflowing inwardly through the inlet/discharge conduit the air bubble isretained in the trap. However, when the air vent in fluid communicationwith the liquid solution reservoir is blocked by the rising water levelin the toilet tank and forms an air-lock between the liquid solutionwithin the liquid solution reservoir and the toilet tank water or whenthe water level in the toilet tank ceases to rise in the event thisoccurs prior to blockage of the air vent, the inward flow of waterthrough the syphon tube and inlet/discharge conduit ceases, and, due tothe geometry of the inlet/discharge conduit, the air trap, and theconnecting passageway joining the syphon tube and the inlet/dischargeconduit, the trapped air bubble relocates itself into the headspacejoining the upper reaches of the inlet/discharge conduit and the syphontube. This isolates the liquid product solution contained in the liquidproduct solution reservoir and the inlet/discharge conduit from thetoilet tank water in the syphon tube until the next flush cycle. As aresult, the solid product, the incompletely dissolved gel and the liquidproduct solution are completely isolated from the surrounding toilettank water during quiescent periods intermediate flush cycles.

To accommodate solid type products which have a substantial tendency toform a gel while dissolving, novel anti-clogging means are providedwithin the product chamber to limit the amount of non-gelled solidproduct exposed to liquid and to maximize the area of contact betweenthe liquid contained within the dispenser and the gelled product. In apreferred embodiment, said anti-clogging means comprise support means inthe lowermost portion of the product chamber for the solid product andlevel control means to control the liquid level within the productchamber. Because the aforementioned solid product support means andlevel control means minimize the area of interface between thenon-gelled solid product and the liquid contained within the dispenserduring quiescent periods, they minimize the quantity of gel formedwithin the dispenser when long periods of time elapse between flushcycles of the toilet. Furthermore, said support means help prevent thegelled portion of said solid product from obstructing the flow of liquidinto and out of the product chamber. Thus, the support means also serveto maximize the area of contact between the liquid contained within thedispenser and the gelled product.

So long as liquid can enter and exit the product chamber during eachflush cycle of the toilet, the gel will continue to dissolve or disperseinto liquid solution which ultimately settles into the liquid solutionreservoir located generally beneath the product chamber. Accordingly,the tendency of the incompletely dissolved gel to clog the presentdispenser is minimized. It is in this manner that the novelanti-clogging means of the present invention helps ensure thatdispensing of a predetermined quantity of liquid solution will occurwith each flush cycle of the toilet.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the present invention, it is believed thepresent invention will be better understood from the followingdescription in conjunction with the accompanying drawings in which:

FIG. 1 is a partially torn away perspective view of a passive dosingdispenser which is an embodiment of the present invention;

FIGS. 2, 3, 5, and 7-10 are simplified, sequential sectional views whichshow a portion of a cycle of the dispenser shown in FIG. 1, said viewsbeing taken along section line 2--2 of FIG. 1;

FIG. 4 is an enlarged fragmentary sectional view of the air trap portionof the dispenser of FIG. 1;

FIG. 6 is an enlarged fragmentary sectional view of the air trap portionof the dispenser of FIG. 1 in the condition illustrated in FIG. 5;

FIG. 11 is a fragmentary sectional view of yet another embodiment of apassive dosing dispenser of the present invention shown as the waterlevel is rising in the toilet tank;

FIG. 12 is a fragmentary sectional view of the dispenser of FIG. 11shown immediately after the water has reached its FULL level in thetoilet tank;

FIG. 13 is a simplified schematic illustration of another embodiment ofthe present invention shown immediately after the water has reached itsFULL level in the toilet tank; and

FIG. 14 is a simplified schematic illustration of still anotherembodiment of the present invention shown immediately after the waterhas reached its FULL level in the toilet tank.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures in which identical features are identicallydesignated, FIG. 1 shows a preferred dispenser 20 embodyinganti-clogging means of the present invention and containing asolid-state, water soluble product 21. Dispenser 20 comprises a frontwall 22, a back wall 23, sidewall segments 25, 26, 31, 50, 51, 52 and90, a top wall 28, bottom wall segments 29, 53 and 54, interiorpartitions 32, 55, 56, 57, 58, 91, 95 and 96, and solid product supportmembers 33. The solid product support members 33 are of lesser thicknessthan the width of the dispenser wall segments to ensure that liquid canwash across the lowermost surface of solid product 21 along its entirelength. The walls and partitions are rigid and define a liquid solutionreservoir 65, a solid product chamber 69, a syphon tube 44 havinguppermost vertical passageways 85 and 86, a horizontal passageway 87, avertical passageway 88 connecting with inlet/discharge conduit 80, saidinlet/discharge conduit having an air trap 81 disposed adjacent thereto,and vent means for the product chamber comprising passageways 71 and 72and air vent 83. The lowermost edge of partition segment 58 isdesignated 59, the lowermost edge of partition segment 96 is designated67, the exposed edge of bottom wall segment 29 is designated 61, thelowermost edge of level control partition 32 is designated 62, theuppermost edge of sidewall segment 31 is designated 93, and thelowermost edge of sidewall segment 26, which in conjunction with frontand back walls 22 and 23, respectively, and sidewall segment 31 defineair vent 83, is designated 64. The inlet/discharge port of dispenser 20located at the lowermost end of syphon tube 44 is designated 78.

In the case of dispenser 20, the lowermost portion of product chamber 69coincides with bottom wall segment 29. Liquid solution reservoir 65 andproduct chamber 69 together comprise what is hereinafter collectivelyreferred to as an internal reservoir.

Referring to FIG. 2, when a dispenser 20 containing solid product 21 isdisposed, for instance, in a toilet tank (not shown) on a bracket orother mounting means (not shown) so that the FULL level of water 63 inthe toilet tank is sufficiently high to at least reach edge 64 ofsidewall segment 26, the dispenser will respond as shown in FIGS. 2-10as the level of water rises to the FULL position in the toilet tank andthe toilet is thereafter flushed.

The dispenser 20 illustrated in FIG. 2 is shown prior to immersion inthe toilet tank water 63. The depth of immersion of solid product 21 iscontrolled by the vertical distance "H" between the uppermost surface ofproduct support members 33 and lowermost edge 62 of level controlpartition 32. Where the solid product 21 has a significant tendency togel, it is preferred to minimize the amount of interface between thesolid product and the liquid contained within the dispenser 20. Thisfactor is particularly important in dispenser embodiments employingproduct chambers which have a relatively small or restricted area offluid communication with the liquid solution reservoir in the dispenser.With dispenser embodiments of the type generally shown in FIG. 1 it hasgenerally been found that vertical distance "H" should be less thanabout 3/8 inch, and most preferably less than about 1/8 inch. Ingeneral, the greater the gelling tendency of solid product 21 and thesmaller the area of fluid communication between the product chamber andthe liquid solution reservoir, the smaller should be the depth ofimmersion "H".

Solid product support members 33 help to ensure that liquid can washacross the lowermost surface of solid product 21 during flush cycles ofthe toilet. Accordingly, they are positioned in the lowermost portion ofproduct chamber 69 and sized so as to minimize flow obstruction. Thestyle and quantity of product support members employed in the practiceof the present invention may take many different forms, such as dowels,planar shelves, or other protuberances secured to the front and/or backwalls or extending from bottom wall segment 29 of dispenser 20. It hasin general been found that for solid products exhibiting a strong gelforming tendency a greater support area is preferred, since this tendsto slow the rate at which solid product 21 settles.

An exemplary dispenser embodiment of the present invention employing twoshelf-like support members secured to and projecting from back wall 23,each of said support members having an overall height of about 0.7inches, as measured from bottom wall segment 29, and an uppermostsurface area of approximately 0.35 square inches each, has been found tofunction without clogging when allowed to stand in 75° F. water forperiods of up to about four days with a surfactant-containing solidproduct of the type generally disclosed in the concurrently filed patentapplication of Clement K. Choy, entitled POLY(ETHYLENE OXIDE)COMPOSITIONS WITH CONTROLLED SOLUBILITY CHARACTERISTICS, Ser. No.153,993 filed May 28, 1980, (Attorney's Docket No. 2791), said patentapplication being hereby incorporated herein by reference. A verticaldistance "H" of about 0.3 inches between the uppermost surface of thesupport members and the lowermost edge of the level control partitionwas employed. The solid product in question initially weighed about 60grams and had a lowermost surface measuring about 2.0 inches in lengthby about 0.5 inches in width.

Referring to FIGS. 3 and 4, as the toilet tank water 63 rises, it enterssyphon tube 44 through inlet/discharge port 78. Air within the upperreaches of the syphon tube is allowed to vent through verticalpassageways 85 and 86, horizontal passageway 87, vertical passageway 88,inlet/discharge conduit 80, liquid product solution reservoir 65, ventpassageways 71 and 72 and air vent 83. As the level of the toilet tankwater 63 continues to rise, FIG. 3, it begins to enter horizontalpassageway 87. Because the difference in elevation of the water in thetoilet tank and the water within the syphon tube is relatively smallprior to air vent 83 becoming blocked, the water head or water pressureavailable to force the water in syphon tube 44 around the loop throughvertical passageway 88 and into inlet/discharge conduit 80 is likewisequite small. To minimize the required driving force to initiate waterflow through the loop, the dispenser 20 preferably employs a series ofpassageways 85, 86, 87 and 88, each of which is smaller in cross-sectionthan any portion of the one immediately preceding it, thereby providingcapillary suction in the direction of flow which tends to draw the waterfrom the syphon tube 44 into the inlet/discharge conduit 80. Thisfeature is more clearly illustrated in the enlarged fragmentary view ofFIG. 4. It is of course recognized that a maximum degree of capillarysuction may be provided by employing passageways 86, 87 and 88 havingcharacteristics similar to passageway 85 which exhibits a continualreduction in cross-section in the direction of liquid flow during thedispenser charging operation. If desired, the entire length of thesyphon tube 44 may be convergent in the direction of water flow duringthe charging operation.

Once toilet tank water 63 enters inlet/discharge conduit 80 and beginsto collect in liquid product solution reservoir 65, the conditionillustrated in FIG. 4 prevails in the air trap 81 disposed adjacentinlet/discharge conduit 80. Namely, an air bubble is retained within theconfines of the air trap 81 defined by partition segments 55, 56, 57 and58. The condition illustrated in FIG. 4 persists as long as toilet tankwater 63 continues to enter the dispenser 20.

When the level 101 of incoming liquid within dispenser product chamber69 reaches lowermost edge 62 of level control partition 32, an air-lockis formed in the uppermost reaches of the product chamber 69, therebypreventing the liquid level 101 from rising further within the productchamber. As shown in FIG. 5, the lowermost portion of solid product 21is thereby immersed a distance "H" into the liquid contained in productchamber 69. It should be noted, however, that the solution level 102 inpassageway 71 continues to rise until such time as the toilet tank water63 contacts lowermost edge 64 of sidewall segment 26 and blocks air vent83, thus providing a secondary air-lock in the uppermost reaches ofpassageway 71 and passageway 72. This secondary air-lock isolates theliquid product solution 103 formed by dissolution of the solid product21 in the toilet tank water introduced during the charging cycle and thetoilet tank water blocking air vent 83. As is apparent from FIG. 5, thelevel 102 of liquid within dispenser passageway 71 is identical to thelevel of toilet tank water 63 in passageway 72. The level 102 of liquidin passageway 71 is distinct from the level 101 of the liquid withinproduct chamber 69 due to the presence of level control partition 32 inthe illustrated embodiment. Should level control partition 32 beeliminated, the dispenser 20 would still function. However, the level ofliquid within the product chamber 69, and hence the depth of immersionof solid product 21, would be controlled exclusively by the verticallocation of air vent 83, assuming the FULL level of the toilet tank isabove the air vent.

In the event the FULL level of the toilet tank is below the air vent 83,the level 102 of liquid in passageway 71 will be identical to the level75 of toilet tank water 63 surrounding the dispenser, while the level101 of liquid within product chamber 69 will be controlled by lowermostedge 62 of level control partition 32. It should, of course, berecognized that there must be sufficient liquid introduced intodispenser 20 to make contact with at least the gel portion 621 of solidproduct 21 in order for the dispenser to form a liquid product by eitherdissolution or dispersion.

In the event level control partition 32 is eliminated and the FULL levelof the toilet tank is below the air vent 83, the level of liquid withinthe dispenser 20 will be identical to the level 75 of toilet tank water63 surrounding the dispenser 20. In all cases, dispenser 20 willfunction to isolate the resultant liquid product solution 103 containedin the upper reaches of product chamber 69 from the surrounding toilettank water 63, whether or not air vent 83 is blocked by toilet tankwater. In the event air vent 83 is blocked by tank water, isolation isprovided by means of an air-lock created in the upper reaches ofpassageway 72. In the event air vent 83 is not blocked by tank water,the vent to atmosphere provides the desired isolation from the toilettank water.

By way of contrast, dispenser embodiment 520 of the present inventionillustrated in FIG. 13 must be so positioned in the toilet tank that theair vent 583 remains vented to atmosphere at all times, i.e., the airvent must be maintained above the FULL level of the toilet tank toensure isolation of the solution contained within the dispenser from thesurrounding toilet tank water.

The dispenser embodiment 520 illustrated in FIG. 13 is, with theexception of reconstruction and relocation of air vent 583, similar todispenser embodiment 20. Solid product support members 533, correspondto solid product support members 33 of dispenser 20, and their uppermostsurfaces are likewise separated by a vertical distance "H" from thelowermost edge 562 of level control partition 532. However, passageway72 has been eliminated from dispenser 20 and passageway 71 has beenvertically extended beyond top wall 28 of dispenser 20 to form a singlevertical passageway 571 in dispenser embodiment 520. Lowermost edge 562of level control partition 532, which corresponds to lowermost edge 62of level control partition 32 in dispenser 20, fixes the level 501 ofthe resultant liquid product solution 503 formed by dissolution of solidproduct 521 within chamber 569, while the level 502 of liquid productsolution 503 in passageway 571 is identical to the level 575 of thesurrounding toilet tank water 563. As will be apparent from aninspection of FIG. 11, air vent 583 must at all times be maintainedabove the FULL level 575 of the toilet tank water 563 to ensureisolation of the liquid product solution 503 from the tank water. Thisis so because, unlike dispenser embodiment 20, vertical passageway 571has no provision for forming an air-lock if the dispenser air vent 583is immersed. Should level control partition 532 be eliminated, liquidlevel control within the product chamber of the dispenser, and hence thedepth of immersion of solid product 521, could be controlled by carefulvertical placement of the dispenser relative to the FULL level of thetoilet tank. A mark or other indicia could be provided on the exteriorof the dispenser to facilitate such placement.

Referring again to FIG. 5, which represents the condition of thedispenser 20 when the toilet tank water level 75 has reached its FULLposition, the bulk of the air bubble retained within air trap 81 duringthe charging operation has rotated about edge 59 of partition segment 58so as to substantially fill horizontal passageway 87 as well as theuppermost portions of vertical passageways 86 and 88, thereby isolatingthe resultant liquid product solution 103 contained within theinlet/discharge conduit 80 from the toilet tank water 63 containedwithin passageway 86 of syphon tube 44. This feature is more clearlyillustrated in FIG. 6, which is an enlarged fragmentary view of the airtrap portion of the dispenser 20 illustrated in FIG. 5. It is thus clearthat the resultant liquid product solution 103 contained withinpassageway 71, product chamber 69, liquid solution reservoir 65 andinlet/discharge conduit 80 is completely isolated from toilet tank water63 by means of the air-lock provided in the uppermost sections ofpassageways 71 and 72 and the air-lock provided in the uppermostsections of passageways 86, 88 and horizontal passageway 87.

As will be appreciated by those skilled in the art, the toilet tankwater brought into contact with solid product 21 during the chargingcycle will continue to dissolve the solid product at least until suchtime as the product solution 103 becomes saturated or until such time asthe toilet is flushed and a predetermined quantity or dose-volume of theliquid solution is dispensed. As will also be appreciated by thoseskilled in the art, the exterior surfaces of solid product 21 arepreferably so configured as to permit a uniform degree of surfaceexposure to the solution 103 along the entire length and width of thesolid product. To this end, the exterior surfaces of the solid productmay be longitudinally grooved, etc.

Solid product compositions for use in automatic toilet tank dispensersmay be specifically formulated to provide cleansing, disinfecting,deodorizing and/or other desired results. One such result foundparticularly useful is treatment of the flush water of toilets in orderto reduce the tendency of such flush water to produce aerosolizationduring the flushing of the toilet. Decreased aerosolization reduces thepossibility of airborne transmission of disease causing organisms fromthe toilet wastewater. Such solid product compositions typicallycomprise a poly(ethyleneoxide)resin, a surfactant and a water-solublesalt. However, it has been found that when solid product compositionscomprising high molecular weight poly(ethylene oxide) resins (i.e.molecular weights of from about 500,000 to about 7,000,000) are utilizedin prior art automatic dispensers, the resin forms a thick gel whenexposed to the limited volume of water within the dispenser, therebyretarding or even completely blocking the subsequent flow of dissolvedand/or dispersed materials out of the dispenser and into the flushwater.

Accordingly, it is highly desirable to provide such solid cakecompositions comprising poly(ethylene oxide), which compositions have areduced tendency to form gels when exposed to water. A particularlypreferred solid product composition having a greatly reduced gel formingtendency is disclosed in the concurrently filed patent application ofClement K. Choy, entitled POLY(ETHYLENE OXIDE) COMPOSITIONS WITHCONTROLLED SOLUBILITY CHARACTERISTICS, Ser. No. 153,993 filed May 28,1980, (Attorney's Docket No. 2791), said patent application beingincorporated herein by reference.

Dispenser embodiments of the present invention have generally exhibitedimproved reliability in dispensing liquid solutions formed by dissolvingsolid products having a gel forming tendency when compared to dispenserembodiments of the type disclosed in FIGS. 1 and 15-18 of the commonlyassigned patent application of Robert S. Dirksing entitled PASSIVEDOSING DISPENSER EMPLOYING TRAPPED AIR BUBBLE TO PROVIDE AIR-LOCK, Ser.No. 002,524, filed Jan. 11, 1979, said patent application beingincorporated herein by reference. The aforementioned improvement inreliability of dispenser embodiments of the present invention is readilydemonstrable with solid-state compositions of the type disclosed in theaforementioned patent application of Clement K. Choy entitledPOLY(ETHYLENE OXIDE) COMPOSITIONS WITH CONTROLLED SOLUBILITYCHARACTERISTICS. The dissolution of such a solid product 21 and thedispensing of a predetermined quantity of liquid solution 103 formedtherefrom in accordance with the present invention is schematicallyillustrated in FIGS. 5-10.

Dissolution of the formula matrix of which such a gel forming solidproduct 21 is comprised typically involves a three stage process. Thefirst stage involves hydration of the solid product 21 to form ahydrated gel 621 illustrated in FIGS. 7-10. The second stage involvesdispersion of the hydrated gel 621 in the lowermost portion of productchamber 69 to form a liquid solution 103 comprised of toilet tank waterand the dissolved solid product 21. The third stage involvesdistribution of the liquid product solution 103 throughout the interiorof the dispenser 20, i.e., throughout liquid solution reservoir 65, thelowermost portion of product chamber 69 and the lowermost portion ofvertical passageway 71.

As is shown in FIG. 5, solid product 21 is initially supported on solidproduct support members 33 when the level 75 of the toilet tank water 63reaches the FULL position. It should be noted that only that portion ofthe solid product 21 located intermediate the uppermost surface ofsupport members 33 and the lowermost edge 62 of level control partition32, i.e., vertical distance "H", is exposed to the water introduced intothe interior of the dispenser 20.

FIG. 7 depicts the condition of the solid product 21 after initiation ofthe gel formation stage. In particular, those portions of the solidproduct 21 in contact with the liquid within the dispenser have begun toform a gel 621. As the gel formed adjacent the uppermost surfaces ofsupport members 33 begins to dissolve and/or disperse, it becomesincapable of supporting the weight of the solid product 21, and thesolid product begins to settle further into the lowermost portion ofproduct chamber 69. This of course exposes more of the solid product tothe liquid solution contained within the dispenser.

FIG. 8 represents a condition of the solid product 21 when the gelportion 621 has nearly contacted the bottom wall segment 29 of thedispenser 20. Provided the accumulation of gel in the lowermost portionof product chamber 69 does not substantially surpass the condition shownin FIG. 8, i.e., does not contact bottom wall segment 29 and block theflow of liquid entering or exiting the lowermost portion of productchamber 69, the dispenser 20 will function as shown in FIGS. 9 and 10 todispense a predetermined quantity of liquid solution 103.

Experience has demonstrated that the liquid solutions formed bydissolution or dispersion of solid-state products which have a stronggel forming tendency are often highly viscous and/or resistant to flow,particularly when allowed to stand for long periods of time. Dispensersincorporating the novel anti-clogging means disclosed herein have beenfound advantageous in dispensing such solutions, even in situationswhere the quiescent periods intermediate flush cycles of the toilet areof long duration. Although the viscous or flow-resistant liquid tends toaccumulate in the lowermost portions of liquid solution reservoir 65during such extended quiescent periods, it has been observed thatdispenser embodiments of the present invention are prone to dischargesuch viscous or flow-resistant materials and thereby unclog themselvesafter several closely spaced flush cycles. This unclogging tendencyappears to be exhibited so long as: (1) the viscous or flow-resistantliquid accumulated in the liquid solution reservoir 65 is capable ofbeing displaced by the small pressure differentials produced by theentering toilet tank water and the exiting liquid solution; and (2)liquid solution is able to enter and exit the lowermost portion ofproduct chamber 69 with each flush cycle of the toilet.

As will be appreciated by those skilled in the art, the greater thegravitational head of the liquid solution contained in the internalreservoir of dispenser 20, the greater will be the available drivingforce during the dispensing cycle. Accordingly, the stronger thetendency of the solid product to form viscous or flow-resistantsolutions, the greater should be the vertical separation between theliquid solution contained in product chamber 69 and passageway 71relative to lowermost edge 67 of interior partition 96.

FIG. 9 represents the condition of the dispenser 20 upon flushing of thetoilet. As the water level 75 begins to fall below the dispenser 20,liquid solution 103 is drawn from the lowermost portion of productchamber 69, the lowermost portion of vertical passageway 71 and fromliquid solution reservoir 65 into syphon tube 44. Because theincompletely dissolved gel portion 621 of solid product 21 does notnormally separate from solid product 21, it is retained within thelowermost portion of product chamber 69 during the dispensing cycle.Accordingly, undissolved gel-like materials are prevented fromobstructing the flow of liquid solution 103 in either the lowermostportions of liquid solution reservoir 65 or the uppermost portions ofsyphon tube 44 during the dispensing cycle.

FIG. 10 represents a point in time when the syphon tube 44 is vented andthe liquid product solution 103 retained therein is being dispensed intothe toilet tank water. Provided the flow of liquid into and out of thelowermost portion of product chamber 69 has not been precluded,dispenser embodiments of the present invention function in a mannersimilar to dispenser embodiments of the type disclosed in FIGS. 1 and15-18 of the aforementioned patent application of Robert S. Dirksingentitled PASSIVE DOSING DISPENSER EMBODYING TRAPPED AIR BUBBLE TOPROVIDE AIR-LOCK, said patent application being incorporated herein byreference.

When the level 75 of the toilet tank water 63 returns to the FULLposition illustrated in FIG. 8, the dispenser 20 will likewise berestored to the condition illustrated in FIG. 8, and the dissolution ordispersion cycle described earlier herein will be re-initiated duringthe ensuing quiescent period, awaiting the next flush cycle of thetoilet.

The dispenser embodiment 20 illustrated in FIG. 1 will discharge apredetermined quantity or dose-volume of liquid product solution 103from the dispenser each time the toilet is flushed. The dose-volume ofsolution is substantially equal to the quantity of solution containedwithin dispenser 20 between lowermost edge 62 of level control partition32 and lowermost edge 67 of partition segment 96 in addition to thecolumn of product solution contained within passageway 71. The amount ofliquid product solution 103 dispensed during each flush cycle is moreeasily understood by comparing FIG. 8, which illustrates the conditionof the dispenser 20 when the toilet tank water level 75 is FULL and airvent 83 has been blocked by the water, with FIG. 10, which illustratesthe condition of the dispenser when the liquid solution level withinliquid solution reservoir 65 has reached lowermost edge 67 of partitionsegment 96 and the dose-volume of solution within syphon tube 44 hasbeen released.

As has been pointed out earlier herein, the solid, water soluble product21 contained in product chamber 69 will pass through a gel phase andultimately dissolve or at least disperse in the water introduced duringeach flush cycle to form liquid product solution 103 until such time asthe solution becomes saturated and equilibrium is achieved or until suchtime as the toilet is again flushed. As has also been pointed outearlier herein, the depth of immersion of solid product 21 is limited tothe vertical distance "H" between the uppermost surface of supportmembers 33 and the lowermost edge 62 of level control partition 32.Accordingly, ignoring buoyant forces, the weight of the solid product 21is carried entirely on support member 33. As the gel 621 of height "H"intermediate the uppermost surface of support members 33 and thenon-gelled portion of solid product 21 dissolves or disperses intoliquid solution 103, the non-gelled portion of the solid product 21 willcontinue to settle, due to gravity, into the lowermost portion ofproduct chamber 69. It is desirable in the practice of the presentinvention that the lowermost surface of solid product 21 dissolve ordisperse substantially uniformly along its length. This avoids bindingor cocking of solid product 21 within the uppermost portions of productchamber 69, and consequent malfunction of the dispenser before the solidproduct has been completely consumed. In addition it ensures that thevolume and surface area of solid product 21 exposed to liquid willremain essentially constant throughout the life of the solid product. Asa result, the strength or concentration of the solution 103 remainsessentially constant throughout the life of the dispenser 20, assumingan adequately long quiescent period for the solution to become saturatedis provided intermediate flush cycles. This condition will prevail atleast until such time as the overall height of the solid product 21becomes less than the vertical distance "H" between lowermost edge 62 oflevel control partition 32 and the uppermost surface of support members33.

While the dispenser embodiment illustrated in FIG. 1 incorporates apreferred air trap 81 disposed adjacent the inlet/discharge conduit 80,the air trap utilized to retain an air bubble during the water chargingoperation may take many different forms. For example, a sudden expansionin cross-sectional flow area could be provided in vertical inletpassageway 88 followed immediately by a sudden contraction in flow areasuch that fluid entering the liquid solution reservoir 65 through theinlet/discharge conduit 80 is unable to exert sufficient force on theair bubble trapped within the expanded flow area to expel it through theliquid solution reservoir 65 and out the air vent 83. Alternatively, theair trap could take the form of a partial obstruction in inlet/dischargeconduit 80, which partial obstruction prevents fluid passing through theconduit from exerting sufficient force on the air bubble retained withinthe trap from being expelled through the liquid solution reservoir 65and out the air vent 83. It is necessary only that the air trap be ofsufficient volume and so located that upon cessation of the flow ofwater past the air trap the air bubble contained therein will attempt torise into the uppermost reaches of the chamber connecting the syphontube and the inlet/discharge conduit so as to completely isolate thetoilet tank water 63 in the syphon tube from the liquid product solution103 contained in the inlet/discharge conduit.

FIG. 11 is a fragmentary sectional view of an alternative embodiment ofa dispenser 320 of the present invention shown during the initial watercharging operation as the level 375 of water 363 in the toilet tank isrising. The dispenser 320 is basically similar to the dispenser 20illustrated in FIG. 1. The illustrated portions of dispenser 320comprise top wall 328, bottom wall segments 329, 353, 354, and 355,solid product support members 333, sidewall segments 326, 331, 350 and351, interior level control partition 332, interior partition 395forming air trap 381 and interior partition segment 396 which inconjunction with the uppermost portion of wall segment 350 formsinlet/discharge conduit 380. As with the embodiment of FIG. 1, a solid,water-soluble product 321 having a gel forming tendency is disposedwithin product chamber 369 such that its lowermost surface rests on theuppermost surfaces of solid product support members 333. The lowermostedge of level control partition 332 is designated 362, and is separatedfrom the uppermost surface of solid product support members 333 by avertical distance "H", similar to dispenser 20 illustrated in FIG. 1.The uppermost edge of wall segment 331 is designated 393, the lowermostedge of sidewall segment 326 is designated 364, the uppermost edge ofsidewall segment 350 is designated 359 and the lowermost edge ofpartition segment 396 is designated 367. Product chamber 369 and liquidsolution reservoir 365 are initially vented by means of passageways 371and 372 and air vent 383 defined by edge 364 of sidewall segment 326,the front and back wall portions (not shown) of dispenser 320 andsidewall segment 331. In the case of dispenser 320, liquid solutionreservoir 365 and product chamber 369 together comprise what iscollectively referred to as an internal reservoir. Syphon tube 344 isdefined by sidewall segments 350, 351 and 390 as well as thecorresponding front and back wall portions (not shown) of dispenser 320.The inlet/discharge port located at the lowermost end of syphon tube 344is designated 378. As with the embodiment illustrated in FIG. 1, theuppermost portions of the syphon tube are convergent, i.e., the radialdistance from uppermost edge 359 of sidewall segment 350 to sidewallsegment 390 and to interior partition 395 continually decreases in thedirection of liquid flow, at least until the point of vertical alignmentwith sidewall segment 350. The air trap 381 formed by interior partition395 is located adjacent the entrance to inlet/discharge conduit 380.

In the condition illustrated in FIG. 11, the toilet tank water 363 hasrisen sufficiently in syphon tube 344 to trap an air bubble within airtrap 381 as it proceeds to fill liquid solution reservoir 365 and thelowermost portions of product chamber 369. As long as the watercontinues to flow within the syphon tube and inlet/discharge conduit,the trapped air bubble will remain within the confines of the air trap381. When, however, air vent 383 is blocked by the rising toilet tankwater 363 as shown in FIG. 12, fluid flow in the inlet/discharge conduit380 ceases, and the trapped air bubble rises, thereby providing air-lockisolation of the liquid product solution 303 and the toilet tank water363 on opposite sides of edge 359 of sidewall segment 350. The productsolution 303 at level 302 within passageway 371 is likewise isolatedfrom the toilet tank water by means of the air-lock contained in theuppermost reaches of passageways 371 and 372. The level 301 of liquidproduct solution 303 within dispenser 320 is defined by lowermost edge362 of level control partition 332 in a manner similar to that describedin connection with embodiment 20 of FIG. 1. The solid productdissolution cycle which takes place within dispenser 320 is essentiallythe same as that of dispenser 20, as shown in FIGS. 5-8. When the toiletis flushed, dispenser embodiment 320 reacts in a manner similar toembodiment 20, as shown in FIGS. 9 and 10. When the level of liquidsolution in liquid solution reservoir 365 reaches lowermost edge 367 ofpartition segment 396, the column of liquid retained within syphon tube344 is vented, thereby dispensing a predetermined quantity of liquidproduct solution 303 into the toilet tank through inlet/discharge port378.

FIG. 14 discloses an alternative dispenser embodiment 720 of the presentinvention. The dispenser embodiment 720 illustrated in FIG. 14 is, withthe exception of relocation of bottom wall segment 729 from the bottomof solid-state product chamber 769 to the bottom of liquid solutionreservoir 765 similar to dispenser embodiment 20 shown in FIG. 1. Solidproduct support members 733 correspond to solid product support members33 of dispenser 20, with the exception that they are supported from theback wall 723 of dispenser 720. The uppermost surfaces of productsupport members 733 are likewise separated by a vertical distance "H"from the lowermost edge 762 of the level control partition 732. Thelowermost edge 762 of level control partition 732, which corresponds tolowermost edge 62 of level control partition 32 in dispenser 20, fixesthe level 701 of the resultant liquid product solution 703 formed bydissolution of solid product 721 within product chamber 769, while thelevel 702 of liquid product solution 703 in passageway 771 coincideswith that in passageway 772 and is controlled by the verticalpositioning of air vent 783 which coincides with lowermost edge 764 ofsidewall 726.

In the condition illustrated in FIG. 14, the level 775 of toilet tankwater 763 has reached its FULL position and the liquid solution 703within dispenser 720 has been isolated from the surrounding tank water.Solid-state product 721 has been immersed in the liquid contained withinthe dispenser a distance "H", and the gel formation stage is just beinginitiated.

As will be apparent from an inspection of FIG. 14, the lowermost portionof product chamber 769 is coextensive with the uppermost portion ofliquid solution reservoir 765 along its entire length. Accordingly,liquid solution 703 within liquid solution reservoir 765 can readilyenter product chamber 769 and contact the lowermost portions of solidproduct 721 along its entire length. This increased area of fluidcommunication between product chamber 769 and liquid solution reservoir765 permits more gel to be formed without precluding liquid containedwithin the dispenser from entering or exiting the product chamber whenthe toilet is flushed. The dispenser 720 shown in FIG. 14 is, therefore,generally preferred over the dispenser 20 shown in FIG. 1 forsolid-state products having more pronounced gelling tendencies.Furthermore, the increased volume of liquid within liquid solutionreservoir 765 results in a greater volume of liquid being dispensed witheach flush of the toilet. In those situations where a saturatedequilibrium state is not reached, this provides a less concentratedliquid solution for a given period of time intermediate flush cycles ofthe toilet, thereby reducing the tendency to form highly viscous and/orflow-resistant solutions.

As will also be apparent from FIG. 14, any gel formed by the immersedlowermost portion of solid-state product 721 is free to project into theuppermost portions of liquid solution reservoir 765 without impairingthe dispensing operation. Furthermore, the downward slant of bottom wallsegment 729 promotes drainage of the liquid from that portion of productchamber 769 nearest sidewall segment 725 into the lowermost reaches ofliquid solution reservoir 765 with each flush cycle of the toilet. Thisliquid movement promotes further dissolution and/or dispersion of thegel associated with solid-state product 721, thereby minimizing thechance of clogging the dispenser.

While the exemplary embodiments of dispensers 20, 320, 520 and 720 maybe constructed by adhesively securing sections of relatively rigidPlexiglas (Registered Trademark of Rohm & Haas Company) to one another,other relatively rigid materials which are substantially inert withrespect to the intended product and aqueous solutions thereof can beused to construct the dispensers. Furthermore, the dispensers may beconstructed or formed at high speed and relatively low cost utilizingvarious manufacturing techniques well known in the art. For example, thedispensers could be vacuum thermoformed in two sections of a materialsuch as polyvinyl chloride having an initial thickness of about 0.02inches, the solid, water-soluble product inserted therebetween and thetwo sections thereafter secured to one another as by heat sealing,adhesives, etc. along a line of contact substantially coinciding withthe location of section line 2--2 of FIG. 1 or section line 10--10 ofFIG. 9. Alternatively the full thickness dispenser configuration may beformed in one segment, the water soluble product inserted therein andthe land areas of the full thickness segment subsequently secured to aplanar segment to form the desired dispenser assembly.

With dispenser embodiments of the present invention, the discharge ofliquid product solution is near the end of the flush cycle. The latterfeature is highly desirable, since it ensures that more of the productsolution dispensed during each flush cycle will be retained in the bowlafter the flush cycle has been completed, and thus will be at a higherconcentration than if it were dispensed during the early portions of theflush cycle. This is so because of the inherent operation of a flushingtoilet. Generally all the water from the toilet tank goes through thetoilet bowl. However, the initial portions of water are used to initiatea syphon action in the toilet bowl which carries away the wastematerial, while the latter portions are used to refill the toilet bowl.By dispensing the product solution into the latter discharged portionsof the tank water a higher solution concentration in the toilet bowl isprovided intermediate flush cycles. If the product solution weredispensed into the initially discharged portions of the toilet tankwater, a large portion of the solution would be carried away with thewaste material so that the concentration of solution remaining in thetoilet bowl would be greatly reduced.

Dispensers of the present invention are particularly well suited forplural component products which need to be isolated from each otherprior to use. Each dispenser section of such a dual or plural productdispenser will maintain a product component in isolation from the toilettank water and from the other product components disposed in otherindependent sections. Such plural product dispensing embodiments couldbe fabricated as a single unit, suspended in the toilet tankindependently of one another, or interdependently suspended in thetoilet tank by means of a common bracket or the like. Because theconstant volume of solution dispensed during each flush cycle mayreadily be determined, it is thus possible to size such plural productdispensers so that each of the product components will be completelyconsumed at about the same point in time, thereby minimizing waste ofany particular component.

While particular embodiments of the present invention have beenillustrated and described, it will be obvious to those skilled in theart that various changes and modifications can be made without departingfrom the spirit and scope of the invention and it is intended to cover,in the appended claims, all such modifications that are within the scopeof this invention. Moreover, while the present invention has beendescribed in the context of dispensing a toilet tank additive, it is notintended to thereby limit the present invention.

What is claimed is:
 1. A passive dosing dispenser for containing aquantity of a liquid solution formed by dissolution of a solid-stateproduct having a gel forming tendency isolated from a body of liquid inwhich said dispenser is immersed and for causing a predetermineddose-volume of said liquid solution to issue from said dispenser inresponse to the level of said body of liquid being lowered from a firstelevation to a second elevation, said dispenser comprising:a. aninternal reservoir for containing a quantity of said liquid solution; b.liquid syphoning means in fluid communication with said reservoir forconveying a predetermined dose-volume of said solution from saidreservoir into said body of liquid in which said dispenser is immersedin response to the level of said body of liquid being lowered from saidfirst elevation to said second elevation, said syphoning means includingpassive means for providing a first air-lock in the path of fluidcommunication between said reservoir and said syphoning means when saiddispenser is immersed in said body of liquid; c. an air vent in fluidcommunication with said reservoir, said air vent including passive meansfor providing a second air-lock in the path of fluid communicationbetween said reservoir and said air vent when said dispenser is immersedin said body of liquid to a depth sufficient to block said air vent,whereby said first air-lock and said second air-lock serve to isolatesaid liquid solution from said body of liquid until such time as saidbody of liquid is lowered from said first elevation to said secondelevation; and d. clog prevention means in said internal reservoir toprevent the gel formed during dissolution of said solid-state productfrom obstructing the flow of said liquid solution within said internalreservoir and said liquid syphoning means.
 2. The passive dosingdispenser of claim 1, wherein said internal reservoir comprises asolid-state product chamber and a liquid solution reservoir locatedbeneath and in fluid communication with said product chamber.
 3. Thepassive dosing dispenser of claim 2, wherein said liquid syphoning meanscomprises a syphon tube having an open lower end and an inlet/dischargeconduit, said inlet/discharge conduit having a top end in fluidcommunication with the upper reaches of said syphon tube and a bottomend in fluid communication with said liquid solution reservoir and saidmeans for providing a first air-lock comprises an air trap disposedadjacent said inlet/discharge conduit and in exclusive fluidcommunication therewith.
 4. The passive dosing dispenser of claim 3,wherein said clog prevention means comprises:a. means to prevent the gelformed during dissolution of said solid-state product from obstructingthe flow of said liquid solution into or out of the lowermost portion ofsaid solid-state product chamber; and b. means for controlling theamount of solid-state product exposed to said liquid solution in saidinternal reservoir.
 5. The passive dosing dispenser of claim 4, whereinthe lowermost portion of said solid-state product chamber isco-extensive with the uppermost portion of said liquid solutionreservoir and is in fluid communication therewith along its entirelength.
 6. The passive dosing dispenser of claim 4 or claim 5, whereinsaid means for controlling the amount of solid-state product exposed tosaid liquid solution in said internal reservoir comprises:a. at leastone solid-state product support member in the lowermost portion of saidsolid-state product chamber; and b. liquid level control means forcontrolling the height of said liquid solution within said solid-stateproduct chamber.
 7. The passive dosing dispenser of claim 6, whereinsaid liquid level control means comprises a level control partitionwithin said solid-state product chamber.
 8. The passive dosing dispenserof claim 7, wherein the lowermost edge of said level control partitionis vertically spaced a maximum of about 3/8 inch from the uppermostsurface of said product support member.
 9. The passive dosing dispenserof claim 6, wherein said liquid level control means comprises said airvent.
 10. The passive dosing dispenser of claim 6, wherein saidsolid-state product support member comprises a protuberance extendingfrom a wall of said product chamber.
 11. A passive dosing dispenser forcontaining a quantity of a liquid solution formed by dissolution of asolid-state product having a gel forming tendency isolated from a bodyof liquid in which said dispenser is immersed and for causing apredetermined dose-volume of said liquid solution to issue from saiddispenser in response to the level of said body of liquid being loweredfrom a first elevation to a second elevation, said dispensercomprising:a. an internal reservoir for containing a quantity of saidliquid solution; b. liquid syphoning means in fluid communication withsaid reservoir for conveying a predetermined dose-volume of saidsolution from said reservoir into said body of liquid in which saiddispenser is immersed in response to the level of said body of liquidbeing lowered from said first elevation to said second elevation, saidsyphoning means including passive means for providing a first air-lockin the path of fluid communication between said reservoir and saidsyphoning means when said dispenser is immersed in said body of liquid;c. an air vent in fluid communication with said reservoir, said air ventextending above said first elevation of said body of liquid when saiddispenser is immersed in said body of liquid, whereby said air-lock andsaid air vent serve to isolate said solution from said body of liquiduntil such time as said body of liquid is lowered from said firstelevation to said second elevation; and d. clog prevention means in saidinternal reservoir to prevent the gel formed during dissolution of saidsolid-stproduct from obstructing the flow of said liquid solution withinsaid internal reservoir and said liquid syphoning means.
 12. The passivedosing dispenser of claim 11, wherein said internal reservoir comprisesa solid-state product chamber and a liquid solution reservoir locatedbeneath and in fluid communication with said product chamber.
 13. Thepassive dosing dispenser of claim 12, wherein said liquid syphoningmeans comprises a syphon tube having an open lower end and aninlet/discharge conduit, said inlet/discharge conduit having a top endin fluid communication with the upper reaches of said syphon tube and abottom end in fluid communication with said liquid solution chamber andsaid means for providing a first air-lock comprises an air trap disposedadjacent said inlet/discharge conduit and in exclusive fluidcommunication therewith.
 14. The passive dosing dispenser of claim 13,wherein said clog prevention means comprises:a. means to prevent the gelformed during dissolution of said solid-state product from obstructingthe flow of said liquid solution into or out of the lowermost portion ofsaid solid-state product chamber; and b. means for controlling theamount of solid-state product exposed to said liquid solution in saidinternal reservoir.
 15. The passive dosing dispenser of claim 14,wherein the lowermost portion of said solid-state product chamber isco-extensive with the uppermost portion of said liquid solutionreservoir and is in fluid communication therewith along its entirelength.
 16. The passive dosing dispenser of claim 14 or claim 15,wherein said means for controlling the amount of solid-state productexposed to said liquid solution in said internal reservoir comprises:a.at least one solid-state product support member in the lowermost portionof said solid-state product chamber; and b. liquid level control meansfor controlling the height of said liquid solution within saidsolid-state product chamber.
 17. The passive dosing dispenser of claim16, wherein said liquid level control means comprises a level controlpartition within said solid-state product chamber.
 18. The passivedosing dispenser of claim 17, wherein the lowermost edge of said levelcontrol partition is vertically spaced a maximum of about 3/8 inch fromthe uppermost surface of said product support member.
 19. The passivedosing dispenser of claim 16, wherein said liquid level control meanscomprises said air vent.
 20. The passive dosing dispenser of claim 16,wherein said solid-state product support member comprises a protuberanceextending from a wall of said product chamber.